In the automotive industry, components, particularly sensors (e.g., for restraint systems), are fastened to the vehicle in various ways, typically by means of screws, rivets or adhesives. Especially for sensors for safety-critical applications (e.g., airbag systems), reliable mounting is of crucial importance. On the one hand, correct mounting must be guaranteed when the vehicle leaves the factory. On the other hand, the sensor must remain safely mounted in the correct location and position or be safely replaceable during repairs or the like throughout its lifetime.
Therefore, the mounting process of present-day sensors that are fastened, e.g., by means of screws is documented in many cases. This may be done by, e.g., monitoring and recording the torque and the angle of rotation during the screwing process of the sensor.
From publication DE 199 23 985 A1, a sensor assembly is known in which the casing of an air pressure sensor used for side-on collision sensing is fastened to a wall in the vehicle by means of fastening means (e.g., screws), wherein the vehicle door preferably has a two-part structure with a dry space facing the interior of the vehicle and a wet space facing the external sheet metal as well as a dividing wall located therebetween. The air pressure sensor is arranged on said dividing wall. On the one hand, the sensor must measure the changes in air pressure in the wet space. On the other hand, the electrical components or at least the plugs and cables must be accommodated in the electrically safe dry space.
To this end, the dividing wall has an opening. The air pressure is transmitted through said opening to what is called a dry-space sensor. Said sensor is arranged in the dry space. The plug of a wet-space sensor is located in the wet space and fastened to an opening of the dividing wall. At the same time, the opening in the dividing wall is closed by adapting the fastening element.
A generic fastening device is known from DE 10 2008 048 318 and counterpart US 2012/0000291, for example. DE 10 2008 048 318 presents a quarter-turn fastener solution instead of a screwed connection. In said quarter-turn fastener, a retaining element having at least one, preferably at least two, retaining wing(s) is rotatably arranged in a supporting element, wherein the retaining wings can be inserted into the opening of the wall in a first rotational position and reach behind the wall in the second rotational position, thereby fastening the supporting element, the retaining element and the assembly located thereon to the wall. In this way, mounting can be performed without tools and fast and yet safely. One or more supporting nose(s) arranged on the supporting element can prevent the supporting element from joining in the rotation, and an additional locking unit can prevent the retaining element from rotating back after a predetermined (e.g., the intended) end position is reached, wherein the retaining element is manually rotated relative to the supporting element by grasping the retaining element.